1. Field of the Invention
This invention relates to a wireless communication system, which has a position registration function and uses a cellular scheme, as well as to a method of controlling this system.
2. Description of the Related Art
An example of a system for specifying present position is a navigation system the medium of which is a GPS (Global Positioning System) in which latitude and longitude are determined from radio-wave information received from a communications satellite in space.
In a system currently available, one specifies one's present position utilizing a navigation system, places a telephone call using a portable telephone and communicates this information to the navigation system of the called party, thereby notifying the called party of one's own position.
Further, in a cellular-type wireless telecommunication system, a wireless base station periodically transmits identification information that is for identifying the wireless base station. Upon receiving the identification information representing the wireless base station, a wireless telecommunication terminal stores this identification information and transmits its own identification information to notify the wireless base station of its own present position. This operation is performed whenever the wireless base station changes. New identification information is stored in place of the old identification information whenever the wireless base station changes.
However, since the system utilizing the GPS in the above-described example of the prior art specifies position by satellite, position information cannot be acquired in case of motion underground, as in a subway or underground passageway, because radio waves from the satellite cannot reach the moving object.
Further, in a case where one's own position is communicated to another party by a portable telephone, one s own position is transmitted by the portable telephone after a response is received. Since this means that one cannot inform of one's own position before communication starts, position information cannot be utilized in judging whether to respond to a communication. Furthermore, if the other party also does not possess map data, notification of position cannot be given.
In addition, information relating to the possessor of a wireless telecommunication terminal cannot be sent to a communicating party.
Further, the automatic position registration function is such that new identification information is stored in place of identification information that has already been stored. However, since a wireless telecommunication terminal recognizes only the new (latest) wireless base station at all times, the wireless telecommunication terminal is incapable of determining via which wireless base stations it has traveled.